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2 more Vray questions


markf
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Still hoping someone can help with my previous window glass post.

 

Attached are 2 renderings. Test01-QMC uses QMC for secondary bounce. Test01-LC01 uses light cache for secondary bounce. Allother settings remain the same.

 

The light cache has really cast a color abour the enire scene. I have tried adjusting secondary bounce multiplier, subdivs and sample size. These have some effect but I cannot get the light cache image to look like the QMC.

 

Any advice on this?

 

Second question- I read that there was a way to see before rendering how long the render will take. Where can I find this?

 

Thanks in advance for any help.

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Vray version 1.5 has an estimated timer for the calculations. The time bounces back and forth depending on what is getting rendered at that time. Example: If your rendering a smooth wall the timer say it'll finish rendering in 5minutes, but when it hits a pane of glass with reflections, the timer will jump up to 10 or 15 minutes to finish.

 

As far as your light cache situation, did you try adjusting the light and dark multiplier in the Color Mapping rollout?

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Joseph,

 

Thanks for your reply. I'm using Vray 1.5. Where do I access this timer?

 

I have not tried the light and dark multiplier in the color mapping. I will have to look into that. It was not covered in the tutorials I have done so far.

 

I'm ne to Vray and sort of stuggling to understand how to control it.

 

Thanks again for your help! This forum comtinues to be invaluable, thanks to the many pros who are willing to offer thier expertise.

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QMC for secondary bounces only does 2 bounces by default.

the lightcache has no limit on bounces, so what you see with the lightcache pic is the physically correct lighting.

the problem is that the calculations are done with gamma 1.0 internally, and the input/output is gamma 2.2 (probably), that's why you are getting excessive color bleeding.

 

the fix is using "linear workflow", which means setting up the gamma correctly and readjusting the material values.

there is tons of info about this topic at the vray forum:

 

http://www.chaosgroup.com/forum/phpBB2/

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I have seen mention of this LWF. Yikes, I'm afraid to get into gamma issues at this stage. Just want to get a decent rendering for now. Hope to look into LWF in the future.

 

Is it possible to use light cache (and not get excessive color bleeding) without going down the LWF road?

 

Thanks for taking the time to reply!

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Thank you for your help. I will use decrease the saturation and see how it goes.

 

I have gotten good results on my first rendering with Vray using QMC for second bounce. There seems to be some very slight noise across most of the walls and ceiling. I'm going to post the image as another thread and see if anyone else can see this noise, thinks it could be elimated and what adjustment to make.

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only,

 

Good question. I'm new to Vray, I have read that LC is the most commonly used second bounce, want to see speed and quality comparison with QMC.

 

Don't have anything else to do but experiment with this kind of stuff...........not

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only,

 

Good question. I'm new to Vray, I have read that LC is the most commonly used second bounce, want to see speed and quality comparison with QMC.

 

Don't have anything else to do but experiment with this kind of stuff...........not

 

 

HAHA i know what u mean..

its all im doing the last 2 weeks..(!)

i just posted a new thread on the subject by the way

 

good luck on your journey :p

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